THE   UNIVERSITY 

OF  ILLINOIS 

LIBRARY 


AGRICULTURAL 
LIBRARY 


UNIVERSITY  OF  ILLINOIS 


BULLETIN  No.  223 


CARNATION  STEM  ROT  AND  ITS  CONTROL 


BY  GEORGE  L.  PELTIER 


URBANA,  ILLINOIS,  SEPTEMBER,  1919 


CONTENTS  OF  BULLETIN  No.  223 

Page 

INTRODUCTION 579 

Stem  Kot  in  Illinois , 579 

Symptoms  of  the  Disease 581 

Carnation   Branch   "Rot 583 

Infection 583 

A  STUDY  OP  THE  CONDITIONS  INFLUENCING  THE  GROWTH  OF  PARASITE  AND 

HOST  584 

The  Fungus  in  Pure  Culture 585 

Persistence  of  the  Fungus  in  Soils 586 

Influence  of  Manures 586 

Commercial  Fertilizers    587 

Acidity  and  Alkalinity  of  the  Soil 588 

Replanting 593 

Temperature 593 

Soil   Moisture    595 

ATTEMPTS  TO  CONTROL  STEM  EOT  IN  THE  GREENHOUSE  BY  DISINFECTION  AND 

STERILIZATION  OF  THE  SOIL 599 

Disinfection  of  the  Soil -. 599 

Steam  Sterilization    602 

CONCLUSIONS  AND  RECOMMENDATIONS   .  606 


BY  GEORGE  L.  PELTIER,  ASSOCIATE  IN  FLORICULTURAL  PATHOLOGY1 

INTRODUCTION 

Carnation  growing  as  a  specialized  industry  in  Illinois  has  assumed 
considerable  proportions  since  its  inception  thirty  years  ago.  It  began 
in  the  vicinity  of  Chicago  and  the  industry  is  still  centered  there. 
Other  large  establishments  are  scattered  thruout  the  state,  and  no 
local  florist  is  without  a  few  benches  of  these  plants.  Accurate 
statistics  are  not  available,  tho  it  is  a  fair  estimate  to  place  the  num- 
ber of  carnation  plants  grown  in  Illinois  for  the  trade  in  a  single 
year  at  five  million  in  the  field  and  three  million  under  glass.2  Allow- 
ing three-fourths  of  a  square  foot  for  each  plant,  the  total  number 
of  plants  under  glass  would  represent  an  area  of  about  two  million 
square  feet,  which  is  approximately  one-fifth  the  total  area  of  glass 
in  Illinois.  It  is  thus  evident  that  several  millions  of  dollars  are 
invested  in  the  carnation  industry  in  Illinois. 

The  carnation  plant  is  attacked  by  a  number  of  fungous  diseases, 
several  of  which  occasionally  result  in  an  appreciable  loss  to  the 
grower.  Perhaps  the  most  serious  of  these  is  carnation  stem  rot. 
The  following  pages  are  devoted  to  a  description  of  some  experi- 
mental work  undertaken  by  the  author  with  the  view  of  controlling 
this  disease.  A  short  discussion  of  the  results,  with  recommenda- 
tions, is  given  at  the  end  of  the  bulletin. 

STEM  ROT  IN  ILLINOIS 

Carnation  stem  rot  is  caused  by  the  attacks  of  a  soil  fungus, 
Rhizoctonia  Solani  Kiihn  (Corticium  vagum  B.  &  C.).3 

The  disease  is  widely  scattered  thruout  the  state,  in  fact,  it  is 
present  to  some  extent  in  every  greenhouse  where  carnations  are 
grown.  The  controlling  influences  in  the  occurrence  of  stem  rot  ap- 
pear not  to  be  due  to  unequal  distribution  of  the  fungus,  but  to  be 
more  closely  related  with  climatic  and  edaphic  conditions  favorable  to 

aSince  September  1,  1916,  Plant  Pathologist,  Ala.  Agr.  Exp.  Sta.,  Auburn, 
Alabama. 

2Based  upon  replies  to  a  questionnaire  sent  in  1915  to  all  Illinois  growers 
having  5,000  square  feet  of  glass  or  more. 

8A  complete  description  of  the  general  characters  of  this  fungus,  together 
with  a  historical  account,  its  distribution,  hosts,  etc.,  will  be  found  in  Bulletin 
189  of  this  station. 

579 


580 


BULLETIN  No.  223 


[September, 


the  spread  and  development  of  the  fungus,  together  with  the  condition 
of  the  plant. 

The  losses  from  carnation  stem  rot  are  not  often  very  great. 
However,  under  conditions  favorable  to  the  rapid  development  and 
spread  of  the  fungus,  it  becomes  a  destructive  parasite.  Under 
such  conditions,  many  cuttings  may  be  destroyed  in  a  short  time 
and  many  plants  also  lost,  both  in  the  field  and  later  in  the  benches. 
In  isolated  cases  the  loss  may  be  as  high  as  50  percent  of  the  cut- 
tings. The  percentage  of  loss  may  be  equally  high  in  the  field  and 
in  benches.  The  average  loss  from  season  to  season  of  course  is 
much  lower.  From  replies  to  questionnaires  sent  out  by  the  writer 
to  carnation  growers  in  the  state,  it  was  learned  that  the  percent- 
age of  loss  varies  from  .1  percent  to  20  percent,  with  an  average 
of  2.2  percent  in  the  greenhouse  and  3.25  percent  in  the  field.  In 
two  of  the  experimental  houses  at  the  Illinois  Experiment  Station  the 
loss  averaged  nearly  2  percent  a  year  for  a  period  of  five  years  (see 
Table  1). 

TABLE  1. — Loss  FROM  CARNATION  STEM  ROT  IN  THE  EXPERIMENTAL  HOUSES 

NOS.    1    AND   2,    FOR    A   PERIOD    OF   FlVE    YEARS 


Season 

Date  of  planting 

No.  of 

plants 

Total 
loss 

Percentage 
loss 

1909-10 

Sept.  9-13  

3200 

33 

1.03 

1910-11 

Sept.  9-12  

3200 

27 

.84 

1911-12 

Aug.  8-10  

3200 

49 

1.53 

1912-13 

Aug.  7-8  

3200 

99 

3.09 

1913-14 

Aug.  12-14  

3200 

86 

2.70 

Practically  all  the  soil  used  by  the  grower  is  inhabited  to  some 
extent  by  this  fungus.  The  fungus  is,  in  all  probability,  endemic, 
that  is,  it  has  not  been  introduced  into  the  state  with  carnation 
plants  but  existed  in  the  soils  of  Illinois  before  carnations  were 
grown.  This  statement  is  supported  by  the  fact  that  diseases  due 
to  the  fungus  are  prevalent  thruout  the  United  States  on  many 
plants,  and  the  fungus  itself  is  found  in  many  foreign  countries. 

The  fungus  may  live  purely  as  a  saprophyte  in  the  soil,  getting 
its  nourishment  from  dead  organic  materials,  or  it  may  be  parasitic, 
that  is,  living  on  and  getting  its  sustenance  from  growing  plants. 
In  a  previous  publication1  the  writer  has  shown  that  the  fungus 
may  attack  a  large  group  of  plants,  including  vegetable  and  field 
crops,  herbaceous  plants,  and  weeds,  besides  many  plants  grown 
under  glass. 

The  wide  distribution,  the  many  hosts,  and  the  repeated  reports 
of  the  destructiveness  of  the  stem-rot  organism  prove  very  conclu- 
sively that  it  persists  indefinitely  under  diverse  conditions  in  arable 


JLoc.  cit. 


1919]  .     CARNATION  STEM  EOT  AND  ITS  CONTROL  581 

soils.  However,  it  is  only  when  conditions  are  favorable  for  its 
development  that  it  becomes  an  active  parasite.  Owing  to  this  fact, 
it  is  not  .as  serious  as  some  of  the  Fusarium  wilts,  which  once  intro- 
duced into  a  locality,  increase  in  severity  each  season  until  the 
growing  of  the  crops  attacked  by  them  must  be  abandoned. 

SYMPTOMS  OF  THE  DISEASE 

Stem  rot  may  attack  seedlings,  cuttings,  or  mature  plants.  In 
ail  cases  the  symptoms  are  more  or  less  alike.  When  seedlings  become 
affected  (a  condition  commonly  known  as  "damping-off  "),  lesions  ap- 
pearing as  small  brown  spots  are  seen  on  the  stem  at  the  surface 
of  the  soil.  The  lesions  increase  in  size,  eventually  almost  girdling 
the  stem  and  causing  the  collapse  of  the  seedling.  In  severe  cases 
the  prostrate  seedlings  may  later  appear  overgrown  with  a  mat  of 
brown  strands  made  up  of  the  mycelium  of  the  fungus. 

Cuttings  are  attacked  several  days  after  they  have  been  placed 
in  the  sand.  As  in  the  case  of  seedlings,  the  cutting  is  attacked  on 
the  stem  just  above,  or  frequently  just  below,  the  surface  of  the  sand. 
The  leaves  wilt,  the  cutting  falls  over,  and  a  soft,  wet,  progressive 
rot  may  develop  at  the  callus  and  extend  to  the  surface  of  the  sand, 
or  lesions  of  various  sizes  may  be  formed  at  any  point. 

Stem  rot  occurs  to  some  extent  on  the  young  plants  in  pots. 
The  source  of  this  infection  is  either  in  the  use  of  diseased  cuttings 
or  of  contaminated  pots.  On  pulling  up  these  plants  it  is  found  that 
stem  rot  usually  starts  from  a  small  lesion  which  increases  in  size 
until  the  stem  is  girdled. 

The  symptoms  shown  by  a  mature  plant  attacked  by  the  disease 
are  very  characteristic  (Fig.  1).  The  fungus  enters  the  stem  at  a 
point  just  below  the  surface  of  the  soil.  The  foliage  becomes  pale, 
gradually  losing  the  green  color.  In  a  few  days  or  a  longer  period, 
depending  upon  the  condition  of  the  weather,  this  is  accompanied 
by  wilting.  An  examination  of  the  stem  at  the  surface  of  the  soil 
reveals  at  this  time  a  slimy,  wet  condition  under  the  bark,  which 
gives  this  rot  its  characteristic  name.  A  slight  twist  is  sufficient  to 
slough  off  the  bark  and  expose  the  harder  tissues  underneath.  A  plant 
at  this  stage  may  as  well  be  pulled  and  removed,  for  it  has  been  in- 
jured beyond  recovery. 

The  fungus  evidently  enters  the  plant  thru  the  cracks  in  the 
corky  layer  of  the  bark  at  a  point  near  the  surface  of  the  soil.  After 
passing  thru  the  bark  it  attacks  the  growing  layer  of  cells,  the  cam- 
bium. From  this  tissue  the  mycelium  passes  into  the  woody  tissues 
and  can  be  found  even  in  the  pith.  It  is  at  this  time  that  wilting 
becomes  evident.  During  later  stages,  sclerotia,  which  are  small  com- 
pact masses  of  mycelium,  are  formed  on  the  center  portions  of  the 
stem  and  these  become  quite  evident  to  the  unaided  eye. 


582 


BULLETIN  No.  223 


[September, 


FIG.  1. — CARNATION  PLANT  SHOWING  THE  CHARACTERISTIC  SYMPTOMS  OF  STEM  EOT 


1919]  CARNATION  STEM  EOT  AND  ITS  CONTROL  583 

CARNATION  BRANCH  ROT 

There  is  but  one  carnation  disease  which  may  be  mistaken  for 
stem  rot.  To  this  disease  the  writer  several  years  ago  applied  the 
.term  "branch  rot".  Before  that  time  the  two  diseases  were  com- 
monly known  as  wet  stem  rot  and  dry  stem  rot.  In  order  to  avoid 
confusion  of  these  two  terms,  the  term  stem  rot  was  adopted  for  the 
disease  caused  by  Rhizoctonia  and  the  name  branch  rot  adopted  to 
replace  the  term  dry  stem  rot. 

Branch  rot  is  caused  by  the  fungus  Fusarium.  This  disease  affects 
the  host  plant  much  more  slowly  than  does  stem  rot.  There  is  no 
noticeably  rapid  wilting  of  the  foliage  of  the  entire  plant.  Infection 
does  not,  as  a  rule,  take  place  at  or  near  the  surface  of  the  soil  but 
may  take  place  at  any  point  where  the  tissues  have  been  broken. 
Branch  rot  is  essentially  a  wound  disease.  Wherever  a  branch  or 
leaf  has  been  broken  or  removed,  the  disease  may  gain  entrance.  In- 
fected parts  turn  yellow,  wilt,  and  become  dry.  A  single  branch  may 
thus  be  affected,  while  the  rest  of  the  plant  appears  healthy  and 
normal.  There  is  no  soft  and  slimy  area  on  the  stem,  as  is  found  in 
stem  rot,  but  instead  the  stem  remains  dry  and  tough.  Occasionally 
both  diseases  occur  on  one  and  the  same  plant. 

In  the  cutting  bench  the  two  diseases  are  not  so  easily  distin- 
guished. However,  careful  observations  will  show  that  in  the  case 
of  branch  rot  the  foliage  is  most  often  affected  and  very  little  rotting 
is  evident  at  or  below  the  surface  of  the  soil.  In  the  case  of  stem 
rot,  on  the  other  hand,  the  disease  is  noticeable  on  parts  of  the  plant 
at  or  below  the  surface  of  the  soil. 

INFECTION 

Mature  Plants. — As  said  above,  stem  rot  attacks  seedlings,  cuttings, 
and  mature  plants.  Mature  plants  may  become  infected  either  in 
the  field  or  in  the  greenhouse.  From  observations  in  the  carnation 
field  during  four  summers  it  has  been  found  that,  altho  always  present 
in  the  soil,  the  fungus  attacks  plants  only  under  certain  conditions. 
One  of  these  conditions  is  the  presence  of  wounds.  Many  counts  in 
the  field  have  brought  to  light  the  fact  that  plants  with  a  single 
central  stem,  breaking  one  to  two  inches  above  the  soil,  are  less 
frequently  infected  than  are  plants  forking  just  at  or  slightly  below 
the  soil  surface.  The  branches  of  the  latter  are  easily  broken  during 
cultivation  and  many  infections  have  been  traced  to  such  wounds. 

Stem  rot  is  more  prevalent  during  a  hot,  sultry,  wet  season.  Such 
a  season  produces  large,  bushy  plants,  with  much  soft  growth.  It  is 
very  probable  that  infection  takes  place  more  readily  under  such 
conditions. 


584  BULLETIN  No.  223  [September, 

Perhaps  the  most  critical  period  of  the  mature  plant  is  at  the 
time  when  it  is  transferred  from  the  field  to  the  house.  The  growth 
of  the  plant  at  this  time  is  more  or  less  checked,  and  unless  the  weather 
is  cool  the  temperatures  of  the  house  may  be  unfavorably  high.  It 
is  at  this  time,  or  shortly  after,  that  large  losses  due  to  Rhizoctonia" 
occur.  Losses  at  this  time  are  unquestionably  due  to  changed  condi- 
tions, more  or  less  abnormal  until  the  plant  has  again  become  estab- 
lished, and  to  unavoidable  injuries  to  the  plant,  such  as  breaking  of 
branches,  etc.,  during  the  process  of  transplanting. 

Cuttings. — Cuttings  in  the  sand  succumb  very  rapidly  to  attacks 
of  Rhizoctonia.  The  fungus  may  be  introduced  into  the  cutting  bench 
by  means  of  cuttings  taken  from  plants  already  infected.  Cuttings 
taken  from  the  lower  portions  of  the  stock  plant  are  most  likely  to 
harbor  the  fungus,  especially  when  the  leaves  have  been  in  contact 
with  soil.  Unclean  sand  also  may  be  the  means  of  infection.  The 
source  of  sand  used  in  the  cutting  bench  is  of  much  importance. 
Sand  used  previously  for  cuttings,  unless  disinfected,  may  harbor 
the  fungus,  which,  when  conditions  are  favorable,  may  become  active 
and  attack  many  cuttings. 

After  the  rooted  cuttings  have  been  transferred  to  pots,  losses  are 
not  frequent.  Individual  plants  may  be  destroyed  by  the  disease,  but 
such  infection  cannot  be  carried  readily  to  adjacent  plants.  If  the 
rooted  cuttings  are  transplanted  into  flats,  the  losses  frequently  are 
more  extensive,  for  a  single  infection  may  readily  be  carried  to  a 
number  of  plants. 

A  STUDY  OF  THE  CONDITIONS  INFLUENCING  THE 
GROWTH  OF  PARASITE  AND  HOST 

In  attempting  to  combat  a  fungous  disease,  such  as  stem  rot 
of  carnations,  two  possible  courses  are  open;  either  the  fungus  must 
be  eradicated  from  the  soil  or,  if  that  is  not  possible,  some  method 
must  be  found  to  reduce  its  destructiveness  to  a  minimum.  Attempt- 
ing the  latter,  two  more  or  less  clearly  defined  methods  of  procedure 
are  possible;  either  the  fungus  must  be  placed  in  an  environment 
which,  being  unfavorable,  will  greatly  reduce  its  virulence  but  at 
the  same  time  approximate  rather  closely  the  optimum  conditions  for 
the  carnation  plant,  or  carnation  plants  must  be  developed  which  are 
to  a  high  degree  immune  from  the  attacks  of  the  fungus. 

A  series  of  experiments  was  undertaken  by  the  author  with  the 
view  of  ascertaining  some  of  the  conditions  which  influence  the 
growth  of  the  fungus ;  also  the  effect  of  these  on  its  parasitism.  Sim- 
ilar studies  were  made  of  possible  methods  of  eradicating  the  fungus 
from  soil  in  greenhouses. 


1919]  CARNATION  STEM  EOT  AND  ITS  CONTROL  585 

THE  FUNGUS  IN  PURE  CULTURE 

Temperature. — In  pure  culture  in  the  laboratory  it  was  found  that 
the  fungus  grows  slowly  at  relatively  low  temperatures.  At  higher 
temperatures  growth  is  more  rapid,  the  most  rapid  growth  taking 
place  at  approximately  86  degrees  Fahrenheit. 

Moisture. — It  was  found  also  that  the  fungus  responds  in  a  simi- 
lar way  to  moisture  conditions.  In  relatively  dry  sand  it  makes 
good  subsurface,  growth.  In  wet  sand  growth  is  on  the  surface  of 
the  sand.  This  is  probably  correlated  with  aeration,  especially 
with  the  supply  of  oxygen.  Practically  all  injury  caused  by  Rhi- 
zoctonia  occurs  at  or  near  the  surface  of  the  soil  and  rarely  below 
three  or  four  inches,  except  perhaps  in  seed  beds  in  which  sand  is 
used.  This  fact  has  already  been  discussed  in  detail  in  Bulletin  189, 
already  referred  to. 

The  stem-rot  organism  is  very  resistant  to  unfavorable  external 
conditions,  such  as  low  temperature  and  drying.  An  experiment  was 
carried  out  by  placing  a  set  of  flasks  partially  filled  with  sand  which 
was  inoculated  with  the  fungus,  in  the  open  field.  Another  set  of 
flasks  containing  some  of  the  inoculated  sand  was  placed  in  the  green- 
house, while  a  third  was  kept  in  the  laboratory.  At  different  times 
during  the  winter  months  the  flasks  were  weighed  to  determine  the 
loss  in  water  content.  Cultures  of  the  fungus  also  were  made  at 
the  same  time  to  determine  whether  it  was  still  living.  During  the 
interim  a  minimum  temperature  of  12  degrees  Fahrenheit  below 
zero  had  been  registered,  and  several  flasks  in  the  open  field  had 
been  broken  by  the  frost.  In  all  cases  the  flasks  had  lost  from  25  to 
50  percent  of  their  original  weight.  However,  in  every  case  the 
fungus  survived  and  was  able  to  make  normal  growth  when  trans- 
ferred to  more  favorable  conditions. 

Cultures  were  made  from  flasks  kept  in  the  laboratory  for  two 
years  and  two  months  after  they  had  been  placed  there,  and  the 
fungus  was  still  alive.  The  sand  at  this  time  was  dry  and  hard. 

Thus,  low  temperatures  and  drying  appear  to  have  little  or  no 
effect  on  the  vitality  of  the  fungus. 

Acidity  and  Alkalinity. — As  a  number  of  writers  have  recom- 
mended the  use  of  lime  for  the  control  of  stem  rot,  the  effects  of 
acidity  and  alkalinity  on  the  growth  of  Rhizoctonia  in  pure  culture 
were  tested  out  in  the  laboratory.  String-bean  agar  was  made  acid 
and  alkaline  to  various  degrees,  inoculated,  and  measurements  of  the 
growth  of  the  mycelium  taken  from  day  to  day.  The  results  showed 
that  Rhizoctonia  can  grow  on  medium  which,  is,  within  reasonable 
limits,  either  acid  or  alkaline  in  reaction. 


586 


BULLETIN  No.  223 


[September, 


PERSISTENCE  OF  THE  FUNGUS  IN  SOILS 

Fortunately  most  growers  renew  the  soil  in  the  benches  each  sea- 
son. However,  as  some  growers  use  the  same  soil,  during  a  second 
season,  a  knowledge  of  whether  the  stem-rot  fungus  will  persist  in 
the  soil  in  the  bench  from  one  year  to  the  next  is  of  importance. 

A  five-foot  section  (No.  113)  in  the  greenhouse  was  filled  with 
soil  taken  from  a  bench  in  which  carnations  had  been  grown  the 
previous  season.  The  bench  was  planted  to  twenty  Beacon  carnation 
plants.  A  similar  section  (No.  112)  was  filled  with  fresh  soil  taken 
from  a  field  that  had  been  in  sod  for  a  number  of  years.  This  section 
was  also  planted  to  twenty  Beacon  plants.  The  two  sections  received 
similar  treatment  in  the  application  of  fertilizers  and  the  cultural 
methods  were  uniform. 

During  the  entire  growing  season  one  plant  died  of  stem  rot  in 
the  section  containing  fresh  soil  (No.  112).  Eight  plants  were  lost 
in  the  section  in  which  old  soil  was  used  (No.  113).  The  results  are 
tabulated  in  Table  2. 


TABLE  2. — EFFECT  OF  PLANTING  CARNATIONS  IN  OLD  INFECTED  SOIL  USED 
THE  PREVIOUS  SEASON:  1912-13 


Sec- 
tion 

Treatment 

Number  of 
diseased 
plants 

Number  of 
healthy 
plants 

Percentage 
loss 

113 

Old  soil  

8 

12 

40.0 

112 

New  soil  

1 

19 

5.0 

The  data  show  clearly  that  Rhizoctonia  persists  in  the  old  soil 
of  the  benches  from  year  to  year.  The  evidence  also  seems  to  indi- 
cate that  the  disease  becomes  more  virulent  in  the  soil  the  second 
season. 

INFLUENCE  OF  MANURES 

To  determine  whether  Rhizoctonia  is  introduced  in  the  bench  thru 
the  use  of  manures,  comprehensive  experiments  were  carried  on  dur- 
ing the  seasons  1912-13  and  1913-14,  with  negative  results. 

Since  greenhouse  soils  receive,  previous  to  the  filling  of  the  benches, 
heavy  applications  of  manures,  it  is  not  improbable  that  such  soils 
offer  a  good  environment  for  the  rapid  growth  of  the  fungus  and 
present  conditions  conducive  to  its  attack  on  the  plant.  A  compari- 
son in  this  respect  was  therefore  made  between  soils  containing  no 
manure  and  soils  receiving  applications  of  different  amounts  of 
manures.  Eight  five-foot  sections  were  filled  with  soil,  manure  was 
added  to  and  incorporated  with  the  soil  of  six  of  them,  while  two 


1919] 


CARNATION  STEM  ROT  AND  ITS  CONTROL 


587 


sections  received  no  manure.  Each  section  was  inoculated  with  the 
fungus  by  mixing  with  the  soil  about  a  bushel  of  infected  soil  taken 
from  benches  in  the  experimental  house  where  plants  had  previously 
succumbed  to  the  disease.  Twenty-five  plants  (variety  Rosette)  were 
planted  in  each  section  and  uniform  treatment  given. 

TABLE  3. — RELATION  OF  VARYING  AMOUNTS  OF  MANURE  IN  THE  SOIL  TO 
THE  VIRULENCE  OF  STEM  ROT:  1914-15 


Sec- 
tion 

Treatment 

Number  of 
healthy 
plants 

Number  of 
diseased 
plants 

Percentage 
loss 

254 
255 

Check:  no  fertilizer  or  manure 
20  pounds  of  manure  

22 
20 

3- 
5 

12.0 
20  0 

256 

40  pounds  of  manure  

25 

0 

0.0 

257 

80  pounds  of  manure  

21 

4 

16.0 

258 

160  pounds  of  manure  

18 

7 

28  0 

259 
260 

Check:  no  fertilizer  or  manure 
40  pounds  of  manure  

21 
25 

4 
0 

16.0 
0  0 

261 

80  pounds  of  manure  

8 

17 

68.0 

The  data  shown  in  Table  3  are  someAvhat  contradictory.  On 
the  whole  it  seems  that  manure  added  to  soil  has  little  influence  on 
the  growth  and  parasitism  of  the  fungus. 

COMMERCIAL  FERTILIZERS 

Table  4  contains  data  of  plants  growing  in  soils  treated  with 
commercial  fertilizers.  The  sections  in  the  experiment  were  inocu- 
lated with  the  fungus  by  adding  to  each  a  pint  of  a  mixture  of  sand 
and  corn  meal  in  which  the  fungus  was  growing.  Twenty-five  Rosette 
carnations  were  planted  in  each  section. 


TABLE  4. — RELATION  OF  EXCESSIVE  AMOUNTS  OF  COMMERCIAL  FERTILIZERS 
TO  THE  VIRULENCE  OF  STEM  ROT  IN  THE  GREENHOUSE:  1914-15 


Sec- 
tion 

Treatment 

Number  of 
healthy 
plants 

Number  of 
diseased 
plants 

Percentage 
loss 

246 

Check  :  no  fertilizer  

8 

17 

68.0 

247 

248 

Dried  blood  1  pound  per  week.  . 
Potassium  sulfate  1  pound  per 
week  

7 
18 

18 

7 

72.0 
28.0 

249 
250 

251 

252 
253 

Dried  blood  1  pound  per  week 
and  4  pounds  limestone1    .... 
Potassium  sulfate  1  pound  per 
week  and  4  pounds  limestone1 
Ammonium  sulfate  1  pound1  .  .  . 
Ammonium  sulfate  2  pounds1  .  . 
Ammonium  sulfate  4  pounds1  .  . 

10 

9 
14 
9 
6 

15 

16 
11 
16 
19 

60.0 

64.0 
44.0 
64.0 
76.0 

limestone  and  ammonium  sulfate  turned  into  soil  before  setting  plants. 


588 


BULLETIN  No.  223 


[September, 


The  data  do  not  show  any  close  relation  between  the  use  of  com- 
mercial fertilizers  and  infection.  In  most  cases  the  commercial 
fertilizers  were  used  in  excessive  amounts.  This  in  all  probability' 
had  an  influence  on  infection  as  a  whole,  for  excessive  amounts  added 
to  soil  lower  the  vitality  of  the  carnation  plant.  This  was  noticeable 
in  the  sections  to  which  potassium  sulfate  was  added,  the  plants  show- 
ing the  usual  symptoms  of  overfeeding  with  potassium.  The  plants 
of  Sections  252  and  253  also  showed  clearly  the  effects  of  the  large 
amounts  of  ammonium  sulfate  used.  The  large  application  of  dried 
blood  in  Section  247  showed  its  effects  on  the  physical  structure  of 
the  soil  and  the  plants  did  not  make  normal  growth.  The  high  per- 
centage of  infection  in  these  sections  is  in  all  probability  correlated 
with  the  weakened  condition  of  the  plants.  Nevertheless,  the  per- 
centage of  loss  in  the  untreated  soils  of  the  check  sections  was  high, 
so  that  no  definite  conclusions  can  be  drawn  from  the  results. 


ACIDITY  AND  ALKALINITY  OF  THE  SOIL 

In  1912  limestone  was  tested  out  next  to  a  section  in  which  sulfuric 
acid  was  used  as  a  possible  control  measure.  Both  of  these  methods 
failing  as  far  as  control  was  concerned,  the  experiments  were  carried 
out  thru  two  more  seasons  to  test  out  the  effects  of  alkalinity  and 
acidity  of  the  soil  and  its  relation  to  stem  rot. 

A  solution  of  sulfuric  acid  was  prepared  and  applied  to  soil  of  a 
five-foot  section  at  the  rate  of  three-sixteenths  fluid  ounce  per  square 
foot.  One  day  previous,  the  soil  was  inoculated  with  Rhizoctonia 
by  mixing  with  it  a  pint  of  infected  soil.  Two  days  after  the  acid 
treatment,  the  section  was  planted  to  twenty  carnation  plants  (variety 
Beacon) . 

A  second  section  was  inoculated  and  planted  the  same  as  the 
first,  while  a  third  was  inoculated  and  five  pounds  of  crushed  lime- 
stone (applied  at  the  rate  of  five  tons  to  the  acre)  was  thoroly  mixed 
with  the  soil  two  days  later.  A  combination  of  the  acid-limestone 
treatment  was  applied  to  a  fourth  section.  The  soil  in  this  section 
also  was  inoculated  and  allowed  to  stand  for  a  day.  The  sulfuric- 

TABLE  5. — EFFECTS  OF  ACIDITY  AND  ALKALINITY  ON  THE  VIRULENCE  OF 
STEM  ROT  IN  THE  GREENHOUSE:  1912-13 


Sec- 
tion 

Treatment 

Number  of 
healthy 
plants 

Number  of 
diseased 
plants 

Percentage 
loss 

109 

Sulfuric  acid,    ,38   fluid  ounce 
per  square  foot   . 

7 

13 

65  0 

110 

Check  

16 

4 

20.0 

111 

Limestone  5  pounds  

19 

1 

5.0 

119 

Sulfuric   acid  plus   5   pounds 
limestone  

15 

5 

25.0 

1919] 


CARNATION  STEM  EOT  AND  ITS  CONTROL 


589 


acid  solution  was  then  applied,  and  on  the  second  day  after  five 
pounds  of  crushed  limestone  was  mixed  with  the  soil. 

The  results  shown  in  Table  5  indicate  that  the  acid  solution  did 
not  control  the  amount  of  stem  rot.  Tests  made  frequently  during 
the  course  of  the  season  gave  good  acid  reactions.  The  addition  of 
crushed  limestone,  however,  appears  to  have  checked  stem  rot. 

The  above  experiment,  with  some  modifications,  was  repeated  dur- 
ing the  seasons  1913-14  and  1914-15.  For  the  first  season  the  same 
amounts  of  acid  and  limestone  were  used,  while  for  the  second  season, 
these  amounts  were  doubled.  The  experiment  was  divided  into  six 
treatments,  two  five-foot  sections  being  devoted  to  each  treatment. 
Each  section  was  planted  to  twenty-five  plants  (variety  White  En- 
chantress) and  all  given  the  same  conditions  thruout  the  season. 
Before  planting,  the  sections  were  treated  as  follows: 

Two  sections  were  inoculated  with  a  soil  culture  of  Rhizoctonia, 
allowed  to  stand  for  several  days,  and  then  given  an  application  of 
sulfuric  acid  at  the  rate  of  three-sixteenths  fluid  ounce  per  square 
foot.  In  1914-15  this  rate  was  doubled.  Two  other  sections  were 
given  an  application  of  sulfuric  acid  at  the  above  rate,  allowed  to 
stand  for  three  days,  and  then  inoculated  with  a  soil  culture  of 
Rhizoctonia.  The  rate  of  application  was  doubled  in  1914-15.  To 

TABLE  6. — EFFECTS  OF  ACIDITY  AND  ALKALINITY  ON  THE  VIRULENCE  OF 
STEM  ROT  IN  THE  GREENHOUSE:  1913-14 


Sec- 
tion 

Treatment 

Number  of 
healthy 
plants 

Number  of 
diseased 
plants 

Total 
diseased 

Percentage 
loss 

167 
173 

168 
174 

169 
175 

170 
176 

171 

177 

172 

178 

Inoculated.     Acid    treat- 
ment   

5 

1 

11 

24 

25 
25 

1 
0 

4 
16 

25 
25 

20 
24 

14 
1 

0 
0 

24 
25 

21 
9 

0 
0 

44 

15 
0 

49 
30 
0 

88.0 

30.0 
0.0 

98.0 
60.0 
0.0 

Inoculated.     Acid    treat- 
ment   

Acid   treatment.     Inocu- 
lated   

Acid   treatment.     Inocu- 
lated   

Acid  treatment.     Check  .  .  . 
Acid  treatment.     Check.  .  . 

Inoculated.     Limestone 
(5  pounds)  

Inoculated.     Limestone 
(5  pounds)  

Limestone  (5  pounds). 
Inoculated  

Limestone  (5  pounds). 
Inoculated  

Limestone  (5  pounds). 
Check  

Limestone  (5  pounds). 
Check  

590 


BULLETIN  No.  223 


[September, 


FIG.  2.— VIRULENCE  CF  STEM  ECT  IN  THE  GREENHOUSE  IN  AN  ACID  SOIL 

(Photographed  Sept.  20,  1914) 
Section  236 — Inoculated.  Acid  Treatment 
Section  237 — Acid   Treatment.  Inoculated 
Section  238 — Acid  Treatment.  Check 


1919] 


CARNATION  STEM  EOT  AND  ITS  CONTROL 


591 


FIG.  3. — AN  ALKALINE  SOIL  INEFFECTIVE  IN  CONTROLLING  THE  VIRULENCE  OF  STEM 

EOT  IN  THE  GREENHOUSE  (Photographed  Sept.  20,  1914) 

Section  239 — Inoculated.  Limestone 

Section  240 — Limestone.  Inoculated 

Section  241 — Limestone.  Check 


592 


BULLETIN  No.  223 


[September, 


two  other  sections  sulfuric  acid  was  applied  at  the  same  rate  as 
above  and  allowed  to  stand  several  days.  Six  additional  sections 
were  treated  in  the  same  way  as  the  six  sections  above,  except  that 
the  acid  treatment  was  in  each  case  replaced  by  5  ^pounds  of  crushed 
limestone.  In  the  1914-15  experiments  10  pounds  of  crushed  lime- 
stone was  used  instead  of  5  pounds.  The  results  of  these  experi- 
ments are  summarized  in  Tables  6  and  7  (see  also  Figs.  2  and  3). 

Under  the  conditions  of  the  above  experiments,  neither  sulfuric 
acid  nor  lime  had  a  controlling  effect  on  stem  rot.  The  fungus  seemed 
to  thrive  equally  well  in  an  acid  soil  and  in  an  alkaline  soil.  This 
result  has  been  corroborated  by  growing  the  fungus  in  the  laboratory 
on  culture  media  of  definite,  known  acidity  and  alkalinity;  within 
certain  limits  the  fungus  showed  but  little  preference  for  either  sub- 
stratum. 


TABLE  7. — EFFECTS  OF  ACIDITY  AND  ALKALINITY  ON  THE  VIRULENCE  OF 
STEM  ROT  IN  THE  GREENHOUSE:  1914-15 


Sec- 
tion 


Treatment 


Number  of 
healthy 
plants 


Number  oi 

diseased 

plants 


Total 
diseased 


Percentage 
loss 


230  Inoculated.     Acid    treat- 

ment   6 

236  Inoculated.     Acid   treat- 

ment   4 

231  Acid   treatment.     Inocu- 

lated    5 

237  Acid   treatment.     Inocu- 

lated...   7 

232  Acid  treatment.     Check ...          25 

238  Acid  treatment.     Check ...          25 

233  Inoculated.     Limestone 

(10  pounds) 10 

239  Inoculated.     Limestone 

(10  pounds) 4 

234  Limestone  (10  pounds). 

Inoculated 6 

240  Limestone  (10  pounds). 

Inoculated 0 

235  Limestone  (10  pounds). 

Check 25 

241  Limestone  (10  pounds). 

Check 25 


19 

21 

20 
18 

0 
0 

15 
21 

19 
25 

0 
0 


40 

38 
0 

36 
44 


80.0 

76.0 
0.0 

72.0 

88.0 

0.0 


1919]  CARNATION  STEM  EOT  AND  ITS  CONTROL  593 

REPLANTING 

Experiments  were  carried  on  for  two  seasons  to  determine  what 
percentage  of  the  plants  survived  when  replanted  under  ordinary 
greenhouse  conditions.  After  a  large  number  of  plants  had  been 
taken  out  of  the  different  sections  in  a  diseased  condition,  they  were 
replaced  by  new  plants.  As  can  be  seen  from  Table  8,  68  to  100  per- 
cent of  the  replants  were  killed  by  stem  rot.  An  average  of  92  per- 
cent for  all  sections  was  lost.  From  these  results  we  can  conclude 
that  the  mortality  of  the  replants  is  extremely  high  and  in  a  few 
cases  only  will  they  survive  thru  a  growing  season. 

TEMPERATURE 

Cultures  of  Rhizoctonia  in  the  laboratory  have  shown  that  the 
fungus  grows  best  at  a  relatively  high  temperature.  The  optimum 
temperature  for  the  growth  of  the  fungus  is  from  86  to  88  degrees 
Fahrenheit.  This  is  much  higher  than  the  optimum  temperature  for 
the  growth  of  the  carnation  plant.  Carnations  in  the  greenhouse 
are  grown,  when  possible,  at  50  to  53  degrees  F.  at  night  and  60 
to  62  degrees  F.  during  the  day.  Altho  the  stem-rot  fungus  will 
grow  at  the  latter  temperatures,  its  growth  is  slow.  These  facts 
indicate  that  there  may  be  a  temperature  relation  between  the  growth 
of  the  parasite  and  host  infection,  and  that  possibly  temperature 
is  the  controlling  factor  in  infection.  Carnation  growers  probably 
are  aware  of  the  fact  that  losses  due  to  stem  rot  are  greater  at 
certain  periods  of  the  year  than  at  others.  The  following  data, 
collected  during  a  period  of  five  years,  show  that  this  is  true.  The 
data  also  tend  to  confirm  the  existence  of  a  more  or  less  definite  rela- 
tion between  temperature  and  loss  by  stem  rot. 

In  Table  9  is  given  the  data  of  the  benching  of  carnation  plants 
for  five  years  and  the  subsequent  losses  of  plants  by  months. 

For  two  seasons  the  plants  were  benched  during  September;  the 
following  three  seasons  they  were  benched  in  August.  From  the 
data  presented  it  is  seen  that  the  greater  losses  occur  during  the 
month  following  that  of  benching.  When  benching  was  done  in  Sep- 
tember, no  loss  occurred  during  that  month,  but  the  greater  loss 
occurred  during  October.  When  benching  was  done  in  August,  the 
greater  loss  occurred  in  September,  and  the  total  loss  was  much  larger 
than  among  the  plantings  benched  in  September.  It  also  is  seen  from 
the  data  that  loss  gradually  decreases  from  the  first  month  after 
benching  to  the  beginning  of  the  warmer  months  of  the  following 
season.  In  Table  8,  also,  the  monthly  loss  is  tabulated,  with  the  same 
results.  During  August,  September,  and  October,  in  the  state  of 
Illinois,  the  outdoor  temperature  is  high  and  the  temperature  in  the 


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BULLETIN  No.  223 


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1919} 


CARNATION  STEM  EOT  AND  ITS  CONTROL 


595 


greenhouses  correspondingly  high.  Beginning  with  November,  lower 
temperatures  prevail  out  of  doors  and  the  temperature  indoors  is 
correspondingly  lower.  With  these  lower  temperatures  there  results 
a  gradual  falling  off  in  plant  losses  due  to  stem  rot. 

During  the  season  1913-14  a  number  of  sections  containing  carna- 
tions were  reserved  in  the  greenhouse  and  one  section  inoculated 
at  the  first  of  each  month,  with  Khizoctonia.  Each  section  contained 
twenty  plants,  sixteen  of  which  were  inoculated  by  placing  infected 
bean  plugs  at  the  base  of  the  stem.  The  remaining  four  plants 
served  as  checks. 


TABLE  10. — EFFECT  OF  SEASONAL  TEMPERATURES  ON  THE  DEATH  RATE  OF 
CARNATION  PLANTS  FROM  STEM  ROT  IN  THE  GREENHOUSE:  1913-14 


Sec- 
tion 

Date  of 
inoculation 

Experiment 
discontinued 

Inoculated  plants 

Check  plants 

Healthy 

Diseased 

Healthy 

Diseased 

143 

Sept.  1,  1913 

Oct.    1,  1913 

1 

15 

4 

0 

140 

Oct.    1,  1913 

Nov.  1,  1913 

3 

13 

4 

0 

139 

Nov.  1,  1913 

Jan.    1,  1914 

10 

6 

4 

0 

138 

Dec.  1,  1913 

Feb.  1,  1914 

8 

8 

4 

0 

137 

Jan.    1,  1914 

Mar.  1,  1914 

14 

2 

4 

0 

134 

Feb.   1,  1914 

Apr.  1,  1914 

3 

131 

4 

0 

133 

Mar.  1,  1914 

May  1,  1914 

12 

4 

4 

0 

132 

Apr.   1,  1914 

June  1,  1914 

9 

7 

4 

0 

131 

May  1,  1914 

July   1,  1914 

0 

16 

4 

0 

130 

June  1,  1914 

July   1,  1914 

2 

14 

4 

0 

128 

July   1,  1914 

July  23,  1914 

6 

10 

4 

0 

*Ten  plants  found  infected  April  1;  only  three  plants  died  during  the 
months  of  February  and  March. 

As  can  be  seen  from  Table  10,  the  death  rate  of  the  plants  inocu- 
lated the  first  two  months  was  high.  This  rate  diminished  markedly 
thru  the  colder  months,  increasing  in  the  spring,  until  in  May  it  had 
again  reached  a  maximum.  During  the  remaining  two  months  this 
same  condition  prevailed,  showing  very  noticeably  the  influence  pf 
temperature  on  mortality. 

SOIL  MOISTURE 

In  1913  the  soil  in  eight  sections  was  inoculated  with  a  soil  culture 
of  Rhizoctonia  and  each  section  planted  to  twenty-five  plants  (variety 
Gloriosa).  The  plants  were  grown  at  the  usual  temperatures  of 
carnations  in  greenhouses  (53-55  degrees  F.  by  night  and  65-70  de- 
grees F.  by  day).  In  order  to  determine  the  influence  of  soil  moisture 
on  death  rate  due  to  stem  rot,  the  various  sections  were  given  different 
applications  of  water.  The  soil  of  two  sections  (Nos.  135  and  136) 
was  kept  uniformly  moist,  the  soil  moisture  being  approximately  that 
which  carnation  growers  attempt  to  maintain  for  the  growth  of  com- 
mercial plants.  The  soil  of  three  sections  (Nos.  126,  144,  and  185) 
was  kept  almost  saturated  by  applying  water  frequently.  The  soil 


596 


BULLETIN  No.  223 


[September, 


of  the  three  remaining  sections  (Nos.  127,  145,  and  166)  was  kept 
dry.  (The  term  dry  does  not  imply  that  no  water  was  applied,  but 
it  means  that  less  water  was  given  the  plants  than  growers  ordinarily 
use  in  growing  carnations.)  As  nearly  as  it  was 'possible  to  do  so, 
the  soil  moisture  of  each  section  was  kept  uniform  and  constant  thru- 
out  the  season. 

Eecords  of  losses  of  each  section  are  tabulated  in  Table  11.  The 
average  losses  for  the  saturated,  the  "normal,"  and  the  dry  sections 
were  36,  22,  and  21  percent  respectively.  These  figures  seem  to 
indicate  that  a  high  degree  of  soil  moisture,  at  the  temperatures  of 
a  carnation  house,  is  favorable  to  infection  by  stem  rot. 

TABLE  11. — EFFECT  OF  SOIL  MOISTURE  ON  VIRULENCE  OF  STEM  ROT  IN  THE 
GREENHOUSE:  1913-14 


Sec- 
tion 

Saturated 

Sec- 
tion 

Normal 

Sec- 
tion 

Low 

No.  of 
plants 
dead 

Percent 
loss 

No.  of 
plants 
dead 

Percent 
loss 

No.  of 
plants 
dead 

Percent 
loss 

126 
144 
185 

5 
9 
13 

20 
36 
52 

135 
136 

7 
4 

28 
16 

127 

145 
166 

2 
10 
3 

8 
40 
14 

In  1914  the  experiment  was  repeated,  with  some  modifications. 
Instead  of  growing  the  plants  at  the  usual  carnation  temperatures,  a 
high  soil  temperature  was  maintained  in  the  benches.  The  under- 
lying reason  for  this  procedure  was  to  determine  whether  the  same 
percentages  of  loss  from  stem  rot  would  occur  thruout  the  season 
and  whether  the  moisture  relation  might  be  of  value  in  an  effective 
control  of  stem  rot.  If  high  temperature — that  is,  a  temperature 
above  that  best  suited  for  carnation  growing — is  instrumental  in  pro- 
voking infection  (as  the  data  of  Tables  8,  9,  and  10  would  lead  one 
to  believe),  then  possibly  the  soil-moisture  factor  might  be  success- 
fully employed  to  counteract  the  influence  of  high  temperatures.  High 
temperatures  of  course  are  often  unavoidable,  especially  at  seasons 
of  the  year  when  the  outdoor  temperature  is  high. 

Four  twenty-foot  benches  were  divided  each  into  four  five-foot 
sections  and  each  section  planted  to  twenty-five  plants  (variety 
Gloriosa).  The  soil  of  the  different  sections  was  inoculated  at  dif- 
ferent times  of  the  year,  as  shown  in  Table  12.  During  the  early 
part  of  the  season  the  air  temperature  was  high,  so  that  no  effort 
was  made  to  control  the  soil  temperature  in  Bench  1.  Later  the 
soil  temperature  was  controlled  by  inclosing,  by  means  of  boards,  the 
area  under  three  benches  (Nos.  2,  3,  and  4).  Previously  an  extra 
steam  pipe,  also,  was  added  to  the  regular  number  of  heating  pipes, 
and  by  means  of  this  increased  radiating  surface  the  temperature  of 
the  soil  in  the  benches  could  be  raised  several  degrees  over  that  of  the 


CARNATION  STEM  EOT  AND  ITS  CONTROL 


597 


temperature  of  the  house.  No  soil  thermograph  being  available,  fre- 
quent readings  were  made  from  a  soil  thermometer  set  from  three  to 
four  inches  into  the  soil.  Thruout  the  winter  the  soil  temperature 
of  Benches  2,  3,  and  4  was  several  degrees  higher  than  was  the  air 
temperature  of  the  house. 

The  soil  of  Section  1  of  each  bench  was  kept  dry,  being  watered 
thoroly  only  when  absolutely  needed.  Section  2  received  a  "normal" 
supply  of  water;  Section  3,  above  normal;  and  Section  4  was  con- 
tinually saturated.  Table  12  gives  the  results  of  the  experiment. 

TABLE  12. — EFFECT  OF  HIGH  TEMPERATURE  AND  SOIL  MOISTURE  ON  THE 

DEATH  RATE  OF  CARNATION  PLANTS  FROM  STEM  ROT  IN 

THE  GREENHOUSE:  1914-15 


Bench 

Dates  of 
inoculation  and 
of  ending  of 
experiment 

Section  4 
Saturated 

Section  3 
Above 
normal 

Section  2 
Normal 

Section  1 
Low 

No.  of 
plants 
dead 

Per- 
cent 
loss 

No.  of 
plants 
dead 

Per- 
cent 
loss 

No.  of 
plants 
dead 

Per- 
cent 
loss 

No.  of 
plants 
dead 

Per- 
cent 
loss 

1 

2 
3 
4 

Aug.  7-Nov.  1... 
Dec.  1-Feb.  1... 
Feb.  1-Apr.  1  ... 
May  1-July  1  ... 

15 

7 
16 
21 

60 
28 
64 

84 

12 

7 
15 
19 

48 
28 
60 
76 

6 
5 
12 
13 

24 
20 
48 
52 

14 
12 
19 
14 

56 
48 
76 
56 

The  data  again  show  that  the  percentage  of  loss  was  higher  in 
the  sections  in  which  the  soil  moisture  was  high.  However,  the  per- 
centage of  loss  was  equally  high  in  the  sections  with  the  dry  soil.  In 
the  latter  case  the  plants  suffered  severely  from  lack  of  water,  as 
was  quite  evident  by  their  appearance,  and  this  weak  condition  of 
the  plants  no  doubt  accounts  for  the  high  percentage  of  infection 
(Fig.  4).  The  important  fact  brought  out  by  the  data  is  that  in  all 
cases  the  percentage  of  loss  from  stem  rot  was  high  in  all  sections 
thruout  the  year,  showing  quite  conclusively  that  soil  temperature 
is  the  limiting  condition  in  the  control  of  stem  rot. 

The  data  also  show  in  a  striking  way  the  double  relation  of  mois- 
ture and  temperature  to  infection.  A  high  soil  moisture  is  favorable 
to  infection ;  a  high  temperature  also  is  favorable  to  infection.  Under 
conditions  of  both  a  high  temperature  and  a  high  percentage  of  soil 
moisture,  the  loss  exceeds  that  of  either  alone.  In  other  words,  soil 
moisture  and  soil  temperature  each  have  an  important  bearing  on 
the  loss  of  carnations  by  stem  rot.  With  either  condition  prevailing 
or  both  conditions  present,  we  have  conditions  very  favorable  for 
the  fungus  infection. 


BULLETIN  No.  223 


[September, 


1919]  CARNATION  STEM  EOT  AND  ITS  CONTROL  599 

ATTEMPTS  TO  CONTKOL  STEM  ROT  IN  THE  GREENHOUSE 
BY  DISINFECTION  AND  STERILIZATION  OF  THE  SOIL 

In  all  the  experiments  discussed  in  the  foregoing  pages  and  under 
this  heading  the  treatment  of  the  soil  in  the  house  was  the  same  as 
described  in  Bulletin  176  of  this  station.  Unless  otherwise  stated  in 
the  experiment,  all  the  sections  were  given  the  same  treatment. 

All  infected  sections  were  inoculated  with  a  two-week-old  soil 
culture  of  Rhizoctonia  figured  and  described  in  Bulletin  189.  For 
the  five-foot  sections  a  one-pint  culture  jar  was  used,  and  for  the  ten- 
foot  sections,  a  one-quart  culture. 

DISINFECTION  OF  THE  SOIL 

Various  soil  disinfectants  have  been  recommended  and  employed 
in  the  treatment  of  soil  in  order  either  to  eliminate  the  parasite  or 
to  so  weaken  its  activities  that  infection  is  greatly  reduced.  Hartley1 
recommends  the  use  of  sulfuric  acid  in  soils  to  prevent  damping-off 
of  pine  seedlings  in  Western  nurseries,  by  Rhizoctonia  and  other 
fungi.  In  his  experimental  work  he  found  an  application  of  the  acid 
in  aqueous  solution,  made  at  the  rate  of  three-sixteenths  fluid  ounce 
per  square  foot  of  soil,  to  be  effective.  Aqueous  solutions  of  formalin 
have  been  recommended  and  are  frequently  used  to  rid  soils  and  plant 
structures,  such  as  tubers  and  seeds,  of  destructive  fungi.  It  is  a 
common  practice  of  carnation  growers  in  replacing  dead  plants  to 
mix  with  the  soil  of  the  replant  a  small  quantity  of  lime  to  ward 
off,  presumably,  the  attack  of  the  fungus.  Various  other  so-called 
disinfectants  have  been  employed  from  time  to  time  and  various  rec- 
ommendations may  be  found  in  the  literature.  The  results  of  different 
investigations  often  are  contradictory,  probably  due  to  the  difference 
in  soils  employed  and  in  the  control  of  conditions  during  the  investi- 
gation.2 

Sulfuric  Acid  and  Lime. — Under  the  heading  of  acidity  and  alka- 
linity of  the  soil  (page  588)  are  given  the  results  of  the  use  of  sulfuric 
acid  and  lime  in  a  carnation  soil.  As  a  control  method  it  failed  abso- 
lutely in  the  three  seasons  it  was  carried  on.  As  can  be  seen  from 
Tables  6  and  7,  a  loss  of  84  percent  occurred  in  the  infected  sections 
treated  with  sulfuric  acid,  and  85  percent  of  the  plants  were  lost  in 
the  corresponding  lime  sections  during  the  two  seasons  1913-14  and 
1914-15. 

Bordeaux  and  Copper  Sulfate. — The  soil  in  three  sixteen-foot  sec- 
tions was  inoculated  with  Rhizoctonia,  watered,  and  allowed  to  stand 


hartley,  Carl.  The  Use  of  Fungicides  to  Prevent  Damping-Off.  Phytopath. 
2,  99.  1912. 

2Another  important  factor,  not  yet  thoroly  understood,  is  the  effect  of 
the  disinfectant  on  the  life  and  activity  of  the  soil  organisms. 


600 


BULLETIN  No.  223 


[September, 


TABLE  13. — RESULTS  OF  BORDEAUX  AND  COPPER-SULFATE  TREATMENTS  ON 
CONTROL  OF  STEM  ROT  IN  THE  GREENHOUSE:  1912-13 


Sec- 
tion 

Treatment 

Number  of 
plants 

Number 
dead 

Percentage 
loss 

106 

Copper  sulf  ate  

32 

13 

40  6 

107 

Check  

32 

3 

9  4 

108 

Bordeaux  

32 

11 

34.4 

for  several  days.  One  section  then  was  drenched  with  Bordeaux 
(4-4-50),  applied  at  the  rate  of  two  gallons  to  ten  square  feet.  Each 
section  was  planted  to  thirty-two  Beacon  plants.  At  the  end  of  the 
season  no  favorable  results  were  evident.  Stem  rot  appeared  in  each 
section;  the  data  (Table  13)  show  even  a  greater  percentage  of  loss 
in  the  treated  section  than  in  the  untreated  section.  Whether  the 
copper  had  an  unfavorable  influence  on  the  carnation  plants  was  not 
determined. 

Formalin. — Formalin  as  a  soil  disinfectant  for  stem  rot  was  tested 
during  three  successive  seasons.  In  August,  1912,  two  ten-foot  sec- 
tions were  inoculated  with  soil  cultures,  watered,  and  allowed  to  stand 
for  several  days.  To  one  section  a  formalin  solution  (1-200)  was 
applied  at  the  rate  of  one  gallon  per  square  foot,  with  a  sprinkler. 


TABLE  14. — RESULTS  OF  FORMALIN  TREATMENT  IN  THE  CONTROL 
CARNATION  STEM  ROT  IN  THE  GREENHOUSE:  1913-14 


OF 


Number 

of  plants 

TV-,*,,! 

Sec- 
tion 

Treatment 

Gloriosa 

White 
Enchant- 

ber 
dead 

local 
number 
dead 

iotal 
percent 
loss 

ress 

144 

Inoculated.     Formalin  .... 

25 

3 

25 

12 

15 

151 

Inoculated.     Formalin  

25 

0 

25 

9 

9 

24 

147 

Formalin.     Inoculated  — 

25 

0 

25 

0 

0 

152 

Formalin.     Inoculated.  .  .  . 

25 

5 

25 

25 

30 

30 

148 

Inoculated  

25 

0 

25 

1 

1 

153 

Inoculated  

25 

6 

25 

23 

29 

30 

149 

Formalin  

25 

0 

25 

0 

0 

154 

Formalin  

25 

0 

25 

0 

0 

0 

150 

Check:  no  treatment  

25 

0 

25 

12 

12 

155 

Check  :  no  treatment  

25 

0 

25 

0 

0 

12 

1919] 


CARNATION  STEM  EOT  AND  ITS  CONTROL 


601 


The  soil  would  not  take  up  all  the  solution  at  one  time,  so  three  appli- 
cations had  to  be  made  during  the  day.  The  bench  was  then  covered 
with  a  tarpaulin  for  a  few  days  to  prevent  a  rapid  loss  of  the  fumes. 
The  soil  was  allowed  to  dry.  On  August  17  both  sections  were  planted 
to  fifty  plants  (variety  Beacon).  During  the  season,  one  plant  died 
in  the  treated  section  and  two  in  the  check.  No  conclusions  can  be 
drawn  from  this  experiment  because  of  the  low  percentage  of  loss 
occurring  in  both  sections. 

In  1913  ten  ten-foot  sections  were  prepared  for  the  formalin  ex- 
periment, and  divided  into  five  treatments  of  two  sections  each.  The 
first  set  was  inoculated  with  soil  cultures  of  Rhizoctonia,  watered,  and 
allowed  to  stand  several  days.  A  solution  of  formalin  (1-120)  was 
then  applied  at  the  rate  of  one  gallon  per  square  foot.  In  the  second 
set  the  soil  was  treated  with  a  like  solution  of  formalin,  allowed  to 
dry,  and  then  inoculated.  The  third  set  of  sections  was  inoculated 
and  allowed  to  stand.  The  soil  in  the  fourth  set  was  treated  with 
formalin  as  in  the  first  set,  while  the  last  two  sections  were  given  no 
treatment  and  served  as  checks. 

Each  section  was  planted  to  twenty-five  Gloriosa  and  twenty-five 
White  Enchantress,  on  August  25,  1913. 

TABLE  15. — RESULTS  OP  FORMALIN  TREATMENT  IN  THE  CONTROL  OP 
CARNATION  STEM  ROT  IN  THE  GREENHOUSE:  1914-15 


Number 

of  plants 

Sec- 
tion 

Treatment 

Gloriosa 

White 
Enchant- 
ress 

Num- 
ber 
dead 

lotal 
number 
dead 

lotal 
percent 
loss 

202 
207 

Inoculated.     Formalin.... 
Inoculated.     Formalin  

25 
25 

25 
25 

11 
9 

13 
20 

20 
33 

53 

203 
208 

Formalin.     Inoculated.  .  .  . 
Formalin.     Inoculated... 

25 

25 

25 
25 

17 
23 

19 
25 

40 
44 

S4 

204 

Inoculated  

25 

17 

209 

Inoculated  

25 

25 

18 
17 

35 

25 

25 

42 

77 

205 

Formalin  

25 

0 

210 

Formalin  

25 

25 

0 
0 

0 

25 

0 

0 

0 

206 

Check  :  no  treatment  

25 

0 

211 

Check  :  no  treatment  .  .    . 

25 

25 

0 
0 

0 

25 

0 

0 

0 

602  BULLETIN  No.  223  [September, 

This  same  experiment  was  repeated  in  1914,  except  that  formalin 
(1-50)  was  applied  at  the  rate  of  one-half  gallon  per  square  foot,  as 
had  been  recommended  by  Johnson1  for  controlling  damping-off. 

The  results  presented  in  Tables  14  and  15  show  that  the  use  of 
formalin  as  a  soil  disinfectant  for  two  years  was  but  a  partial  suc- 
cess. The  loss,  even  after  the  application  of  the  formalin,  varied 
from  24  to  53  percent  (see  Fig.  5).  In  the  sections  in  which  the  soil 
was  not  artificially  inoculated  prior  to  the  application  of  the  formalin, 
no  losses  are  recorded.  This  may  be  due,  however,  to  the  possibility 
that  the  organism  was  not  present  in  the  soil,  for  in  the  check  sections 
of  the  last  series  no  stem  rot  occurred. 

STEAM  STERILIZATION 

A  sterilizing  box  measuring  4  feet  by  16  feet  by  20  inches  was 
constructed  of  two-inch  boards.    It  was  divided  into  two  equal  com-  - 
partments  for  the  simultaneous  sterilization  of  soil  artifically  inocu- 
lated and  of  soil  not  inoculated.     Another  sterilizing  box,  4  feet  by 
8  feet  by  10  inches,  was  built  for  the  purpose  of  sterilizing  manure. 

The  large  box  was  fitted  with  four  perforated  steam  pipes,  run- 
ning lengthwise,  12  inches  apart  and  about  6  inches  from  the  bottom. 
The  perforations  in  the  pipes  were  %6  inch  in  diameter  and  12  inches 
apart,  alternating  in  position  on  two  adjacent  pipes.  By  means  of 
T's  and  L's  the  pipes  in  the  box  were  connected,  thru  a  valve,  with 
a  pipe  leading  directly  to  the  boiler.  The  latter  contained,  at  a  point 
beyond  this  connection,  another  valve  by  means  of  which  all  water 
and  wet  steam  could  be  released  prior  to  forcing  the  steam  into  the 
soil  box.  A  lid  of  boards  completed  the  sterilizing  apparatus. 

The  smaller  box  contained  three  steam  pipes  connected  in  a  simi- 
lar way  with  the  pipe  leading  to  the  boiler.  After  filling  the  compart- 
ment with  soil,  dry  steam  was  forced  thru  the  pipes  at  forty  pounds 
pressure  for  one  hour. 

In  case  the  soil  was  to  be  inoculated,  the  amount  necessary  to  fill 
a  section  of  bench  was  calculated,  a  soil  culture  of  Ehizoctonia  added, 
the  whole  thoroly  mixed,  watered,  covered,  and  allowed  to  stand  sev- 
eral days  before  sterilization. 

After  the  sterilization  was  complete,  the  lid  was  removed  and  the 
soil  allowed  to  cool.  It  was  then  taken  into  the  greenhouse  in  disin- 
fected wheelbarrows. 

The  experiment  was  begun  in  1912  by  using  two  sections  of  bench, 
each  ten  feet  long.  The  soil  of  one  section  was  inoculated  with  the 
fungus,  and  after  several  days  was  steam  sterilized;  the  soil  of  the 
second  section  was  inoculated  but  not  sterilized.  Each  section  was 

'Johnson,  J.  The  Control  of  Damping-off  Disease  in  Plant  Beds.  Wis 
Agr.  Exp.  Sta.  Ees.  Bui.  31,  29-61.  1914. 


1919} 


CARNATION  STEM  EOT  AND  ITS  CONTROL 


603 


604 


BULLETIN  No.  223 


[September, 


TABLE  16. — RESULTS  OF  STEAM  STERILIZATION  IN  THE  CONTROL  OP  STEM 
ROT  IN  THE  GREENHOUSE:  1912-13 


Sec- 
tion 

Treatment 

Number  of 
plants 

Number 
•dead 

Percentage 
loss 

101 

Inoculated.     Sterilized  

52 

0 

0 

102 

Inoculated.     Check  

52 

38 

73 

planted  (August  9)  to  fifty-two  plants  of  Beacon  carnations.  The 
losses  are  tabulated  in  Table  16.  No  loss  of  plants  occurred  in  the 
sterilized  soil;  in  the  unsterilized  soil  73  percent  of  the  plants  were 
lost  by  the  disease. 

During  the  season  of  1913-14  and  1914-15  the  experiment  was 
repeated  on  a  larger  scale.  Five  ten-foot  sections  were  used,  each  in 
duplicate.  The  soil  of  the  first  set  was  inoculated  and  sterilized; 
that  of  the  second  set  was  sterilized  and  then  inoculated;  the  soil 
of  the  third  set  was  inoculated  only ;  that  of  the  fourth  set  was  steril- 
ized only.  The  soil  of  the  fifth  set  received  no  treatment  and  served 
as  a  general  check. 

The  results  are  brought  together  in  Tables  17  and  18.  In  all  cases 
where  steam  sterilization  was  used  no  loss  of  plants  occurred.  In  all 


TABLE  17. — RESULTS  OF  STEAM  STERILIZATION  IN  THE  CONTROL  OF 
ROT  IN  THE  GREENHOUSE:  1913-14 


STEM 


Number 

of  plants 

TYvtol 

TY>±nl 

Sec- 
tion 

Treatment 

Gloriosa 

White 
Enchant- 
ress 

ber 
dead 

number 
dead 

percent 
loss 

156 
161 

Inoculated.     Sterilized  
Inoculated.     Sterilized  

25 
25 

25 
25 

0 
0 

0 
0 

0 
0 

0 

157 
162 

Sterilized.     Inoculated  
Sterilized.     Inoculated  

25 
25 

25 
25 

21 
25 

1 

2 

46 
3 

49 

158 

Inoculated  

25 

9 

163 

Inoculated  

25 

25 

23 

8 

32 

25 

25 

33 

65 

159 

Sterilized  

25 

0 

164 

Sterilized  

25 

25 

0 
0 

0 

25 

0 

0 

0 

160 

Check:  no  treatment  .    . 

25 

0 

165 

Check:  no  treatment  

25 

25 

0 
0 

0 

25 

0 

0 

0 

1919] 


CARNATION  STEM  ROT  AND  ITS  CONTROL 


605 


TABLE  18.— ^RESULTS  OF  STEAM  STERILIZATION  IN  THE  CONTROL  OF  STEM 
ROT  IN  THE  GREENHOUSE:  1914-15 


Number 

of  plants 

Sec- 
tion 

Treatment 

Gloriosa 

White 
Enchant- 
tress 

her 
dead 

number 
dead 

percent 
loss 

216 
221 

Inoculated.     Sterilized  
Inoculated.     Sterilized  

25 
25 

25 
25 

0 
0 

0 
0 

0 
0 

0 

217 
222 

Sterilized.     Inoculated  
Sterilized.     Inoculated  — 

25 
25 

25 
25 

1 

19 

10 
24 

20 
34 

54 

218 

Inoculated  

25 

18 

223 

Inoculated  

25 

25 

21 

22 

39 

25 

25 

47 

86 

219 

Sterilized  

25 

0 

224 

Sterilized  

25 

25 

0 
0 

0 

25 

0 

0 

0 

220 

Check:  no  treatment  

25 

0 

225 

Check  :  no  treatment  

25 

25 

0 
0 

0 

25 

0 

0 

0 

sections  in  which  the  fungus  was  introduced  and  not  sterilized,  the 
losses  ranged  from  49  to  86  percent  (see  Fig.  5).  Why  no  losses 
occurred  in  the  untreated  sections  is  difficult  to  explain,  unless  it 
may  be  inferred  that  the  fungus  was  not  present  in  the  soil. 

Records  were  kept  of  the  production  of  flowers  by  the  plants  in 
the  various  sections.  These  records  are  given  in  Tables  19  and  20. 
In  no  case  was  production  affected  by  the  soil  sterilization  process. 

TABLE  19. — EFFECT  OF  STEAM-STERILIZED  SOIL  ON  PRODUCTION  AND  QUALITY 
OF  CARNATION  FLOWERS:  1913-14 


Sections 

Treatment 

No.  of 
flowers 

Perfect 

Size 

Stem 
length 

Firsts 

Gloriosa 


156,  161 

Sterilized  

No. 
584 

No. 
562 

percent 
98.2 

inches 
2.79 

inches 
17.81 

No. 
470 

percent 
80.5 

160,  165 

Check  

579 

565 

97.5 

2.76 

17.09 

259 

44.7 

159,  164 

Sterilized  

568 

552 

97.2 

2.76 

17.07 

396 

70.0 

White  Enchantress 


156,  161 

Sterilized.  .  .  . 

863 

706 

81.2 

3.11 

14.74 

758 

87.8 

160,  165 

Check  

773 

713 

92.2 

3.12 

14.76 

643 

83.8 

158,  164 

Sterilized  

819 

660 

81.8 

3.11 

14.64 

637 

77.7 

606 


BULLETIN  No.  223 


[September, 


TABLE  20.- 


-EFPECT  OF  STEAM-STERILIZED  SOIL  ON  PRODUCTION  AND  QUALITY 
OF  CARNATION  FLOWERS:  1914-15 


Sections 

Treatment 

No.  of 
flowers 

Perfect 

Size 

Stem 
leflgth 

Firsts 

Gloriosa 


216,  221 

Sterilized  

No. 
591 

No. 
577 

percent 
97.6 

inches 
2.87 

inches 
20.53 

No. 
508 

percent 
89  3 

220,  225 

Check  

570 

533 

93.5 

2.83 

19.73 

479 

84.0 

219,  224 

Sterilized  

579 

563 

97.2 

2.86 

19.12 

475 

82.0 

White  Enchantress 


216,  221 

Sterilized  

721 

679 

94.1 

3.18 

18.83 

701 

97.2 

220,  225 

Check  

705 

674 

95.6 

3.16 

18.69 

674 

95  7 

219,  224 

Sterilized  

762 

689 

90.4 

3.09 

19.00 

737 

96.7 

CONCLUSIONS  AND  RECOMMENDATIONS 

From  the  data  and  experimental  evidence  presented  in  this  bulletin 
it  seems  clear  that  the  control  of  stem  rot  of  carnations  lies  along 
the  line  of  careful  control  of  growing  conditions  of  the  carnation 
plant  and  in  the  use  of  a  clean  ^oil.  The  disease  is  a  soil  disease. 
The  organism  lives  in  the  soil,  under  ordinary  conditions  as  a 
saprophyte,  but  under  more  favorable  conditions  attacking  the  carna- 
tion plant  and  causing  its  destruction.  The  conditions  influencing  its 
spread  and  development  are  high  soil  temperature  and  soil  moisture. 

Soil  Disinfectants  of  Little  Value. — The  results  of  these  experi- 
ments indicate  that  the  usual  soil  disinfectants,  such  as  sulfuric  acid, 
lime,  Bordeaux,  copper  sulfate,  and  formalin,  applied  to  the  soil  have 
but  little  effect  on  the  fungus  and  that  they  are  consequently  of  little 
value  as  a  means  of  controlling  the  disease.  No  chemical  solution  was 
found  which,  when  applied  to  the  soil  in  quantities  not  harmful  to 
the  plant,  eradicated  the  fungus.  The  fungus  is  very  resistant  in  soil 
to  weak  solutions  of  acids  and  alkalies.  It  is  also  resistant  to  low  tem- 
peratures and  drying.  Evidence  is  presented  that  it  lives  in  soils  for 
years,  resisting  all  the  rigorous  conditions  of  a  cold  winter  and  a 
hot  summer. 

Steam  Sterilization  Effective. — In  order  completely  to  eradicate 
the  fungus  from  the  soil,  steam  sterilization  alone  seems  to  be  effective. 
Dry  steam  forced  thru  the  soil  at  forty  pounds  pressure  for  one  hour 
will  destroy  the  fungus.  There  is  no  indication  that  such  steriliza- 
tion of  soil  is  accompanied  by  evil  effects  on  the  growth  or  the  pro- 
duction of  carnation  plants.  Sterilized  soil  grows  equally  good 
carnation  plants  as  unsterilized  soil.  However,  aside  from  the  labor 
and  expense  involved  in  sterilization,  unless  the  plants  brought  in 
from  the  field- are  free  from  the  disease  organism  the  disease  may 
again  be  introduced  into  the  soil  of  the  benches.  There  is  of  course 


1919]  CARNATION  STEM  EOT  AND  ITS  CONTROL  607 

but  little  assurance  that  the  fungus  is  not  present  in  the  field.  In 
order  to  prevent  the  introduction  of  the  disease  from  the  field  into  the 
benches,  only  healthy  and  uninjured  plants  should  be  used.  Every 
plant  should  be  carefully  examined  at  the  crown  for  evidences  of  the 
disease  and  any  plant  showing  symptoms  should  be  discarded. 

Importance  of  Low  Temperature  and  Minimum  of  Moisture. — 
The  first  month  the  plant  is  in  the  bench  is  the  most  critical  point  in 
the  life  of  the  plant,  especially  if  the  transplanting  is  done  early.  The 
temperature  of  the  greenhouse  is  high  at  this  time,  and,  still  more 
important,  owing  to  the  large  amount  and  the  frequent  use  of  water 
concomitant  with  transplanting,  the  humidity  of  both  soil  and  air 
is  high.  Experiments  have  shown  that  high  temperature  and  high 
water  content  of  soil,  especially  when  existing  simultaneously,  offer 
a  most  favorable  environment  to  the  fungus.  High  temperatures  in 
the  cutting  bench  and  in  the  carnation  house  give  Rhizoctonia  a  two- 
fold advantage;  they  lower  the  vitality  of  the  cuttings  and  plants 
and  give  the  fungus  optimum  conditions  under  which  to  develop.  In 
other  words,  when  normal  temperature  for  the  best  development  of 
the  plant  is  furnished,  no  stem  rot  occurs ;  while  if  high  temperatures 
are  maintained,  the  vitality  of  the  plant  is  lowered,  thus  making  it 
more  susceptible  to  stem  rot.  At  the  same  time,  high  temperatures 
favor  the  growth  of  the  fungus,  increasing  its  virulence.  A  careful 
watch,  therefore,  of  the  growing  conditions  of  the  plants  is  necessary 
at  this  time.  The  temperature  should  be  kept  as  low  as  possible  and 
no  more  water  applied  to  the  soil  than  is  absolutely  necessary  for 
a  healthy  growth  of  the  plant. 

Seedlings  and  Cuttings. — These  statements  apply  also  to  the  grow- 
ing of  seedlings  and  cuttings.  Steam  sterilization  of  soil  and  sand 
is  recommended  whenever  it  is  possible.  The  cutting  bench  offers 
a  most  favorable  environment  for  the  growth  of  the  fungus  if  it  is 
present  in  the  sand.  A  relatively  high  temperature  and  high  per- 
centage of  moisture  of  the  sand,  as  well  as  the  high  humidity  of  the 
air  resulting  from  artificial  shading,  are  characteristic  of  the  cutting 
bench.  Under  such  conditions  it  is  extremely  difficult  to  control 
damping-off  if  it  is  present  in  the  sand.  It  is  therefore  recommended 
that  the  sand  be  sterilized  with  steam  and  careful  attention  given 
later  to  the  moisture  and  temperature  conditions.  A  relatively  high 
temperature  of  soil  together  with  a  high  percentage  of  moisture  is 
conducive  to  infection.  It  is  important,  therefore,  that  the  tempera- 
ture be  "kept  as  low  as  possible  for  a  good  healthy  growth  of  the 
carnation  plant.  This  temperature,  since  it  is  lower  than  that  of 
the  optimum  temperature  of  the  fungus,  will  prove  an  important 
factor  iu  the  control  of  infection. 


AUTHOR  INDEX 


(500 


AUTHOR  INDEX 


Bull,  Sleeter,  Grindley,  H.  S., 
Mumford,  H.  W.,  and  Em- 
niott,  A.  D.  Fertilizing  Con- 
stituents Excreted  by  Two- 
year-old  Steers '.  .  .  .  127-162 

Bm-lison,  W.  L.,  and  Stark,  E.  W. 

Spring  Wheat  for  Illinois. 313-320 

Crandall,  Charles  S.  Apple-Bud 
Selection :  Apple  Seedlings 
from  Selected  Trees 179-264 

Kmmett,  A.  D.,  Grindley,  H.   S., 
Mumford,   H.  W.,   and  Bull, 
Sleeter.     Fertilizing  Constit- 
uents Excreted  by  Two-year-  , 
old  Steers  .".127-162 

Fahrnkopf,  H.  F.  T.,  Hopkins, 
Cyril  G.,  Garrett,  F.  W., 
and  Whitchurch,  J.  E.  Illi- 
nois Crop  Yields  from  Ex- 
periment Fields 397-504 

Garrett,  F.  W.,  Hopkins,  Cyril  G., 
Whitchureh,  J.  E.,  and 
Fahrnkopf,  H.  F.  T.  Illinois 
Crop  Yields  from  Experi- 
ment Fields  397-504 

Grindley,  H.  S.,  Mumford,  H.  W., 
Emmett,  A.  D.,  and  Bull, 
Sleeter.  Fertilizing  Constit- 
uents Excreted  by  Two-year- 
old  Steers  '.127-162 

Grindley,  H.  S.,  and  Busk,  H.  P. 
Field  Investigations  of  For- 
age Poisoning  in  Cattle  and 
Horses  161-176 

Gunderson,  A.  J.  Field  Experi- 
ments in  Spraying  Apple 
Orchards  for  the  Control  of 
Apple  Blotch  549-576 

Gunderson,  A.  J.  The  Pruning 
of  Winter-Injured  Peach 
Trees 381-394 

Hopkins,  Cyril  G.,  Garrett,  F.  W., 
Whitchurch,  J.  E.,  and 
Fahrnkopf,  H.  F.  T.  Illinois 
Crop  Yields  from  Soil  Ex- 
periment Fields 397-504 


PAGE 

Mosier,  J.  G.  Climate  of  Illi- 
nois   1-126 

Mumford,  H.  W.,  Grindley,  H.  S., 
Emmett,  A.  D.,  anil  Bull, 
Sleeter.  Fertilizing  Constitu- 
ents Excreted  by  Two-year- 
old  Steers  127-162 

Pearson,  F.  A.  The  Cost  of  Milk 
Production  Computed  on  the 
Year  Basis  341-364 

Peltier,  George  L.  Carnation 

Stem  Rot  and  its  Control. 577-608 

Peltier,  George  L.  Snapdragon 

Rust 533-548 

Rusk,  H.  P.,  and  Grindley,  H.  S. 
Field  Investigations  of  For- 
age Poisoning  in  Cattle  and 
Horses 161-176 

Stark,  R.  W.,  and  Burlison,  W.  L. 

Spring  Wheat  for  Illinois .  313-320 

Stevens,  Frank  Lincoln.  An  Ap- 
ple Canker  Due  to  Cyto- 
spora '365-380 

Stevens,  Frank  Lincoln.  Two  Illi- 
nois Rhubarb  Diseases.  .  .297-312 

Stevens,  Frank  Lincoln,  and  True, 
Esther  Young.  Black  Spot 
of  Onion  Sets 505-532 

Stewart,  Robert,  and  Wyatt,  F. 
A.  Limestone  Action  on  Acid 
Soils 265-296 

True,  Esther  Young,  and  Stevens, 
Frank  Lincoln.  Black  Spot 
of  Onion  Sets 505-532 

Whitchurch,  J.  E.,  Hopkins,  Cyril 
G.,  Garrett,  F.  W.,  and 
Fahrnkopf,  H.  F.  T.  Illi- 
nois Crop  Yields  from  Ex- 
periment Fields  397-504 

Wyatt,  F.  A.,  and  Stewart, 
Robert.  Limestone  Action  on 
Acid  Soils 265-296 

Yapp,  W.  W.  A  Study  of  the 
Relative  Reliability  of  Offi- 
cial Tests  of  Dairy  Cows. 321-340 


610 


VOLUME  15 


INDEX 


(The  headings  in  capitals  are  subjects  of  entire  bulletins) 


PAGE 

Acidity  of  soil,  influence  on  car- 
nation stem  rot 588-92 

Aledo      experiment     field,      Crop 

yields  in  soil  experiments. 405,  407 
Alfalfa,    germination    at    various 

temperatures 25 

Alkalinity  of  soil,  effect  on  car- 
nation stem  rot 588-92 

Anthracnose,   on   onion   sets 507 

Ehubarb 299-308 

Anticyclones,     Weather     changes 

produced  by 5,  9 

Antioch    experiment    field,    Crop 

yields  in  soil  experiments. 406,  407 

Antirrhinum  ma  jus    535,  540,548 

Apple  blotch 

Recommendations     for     control 

of 575 

Spraying  for  control  of 549-75 

Weather  conditions  affecting.  .   553 
Apple-bud  selection 

Comparative  value  of  buds 
from    different    locations    on 

shoot 232-50 

from    different    Ideations    on 

tree 202-31 

Comparative    value    of    robust 

and  slender  scions 250-52 

Conclusions 263-64 

Effect    of    vigor    of    stock    on 

growth 252 

Influence  of  care  in  grafting.  252-53 

Test  of  size 183-202 

Varietal  and  individual   differ- 
ences   253-54 

APPLE-BUD  SELECTION:    AP- 
PLE    SEEDLINGS     FROM 
SELECTED   TREES ....  179-264 
APPLE     CANKER     DUE      TO 

CYTOSPORA,  AN 365-79 

Bibliography 377-79 

Description 367-68 

Fungus 368-72 

APPLE      ORCHARDS,     FIELD 
EXPERIMENTS    IN 
SPRAYING,  FOR  CON- 
TROL OF  APPLE 

BLOTCH 549-75 

Apple  seedlings,  tests  with,  from 

selected  trees 254-64 

Black  spot  of  onion  sets 505-32 

See  also  Onion  sets 


PAGE 


Bloomingtou  experiment  field, 
Crop  yields  in  soil  experi- 
ments   408,410 

Blotch,  Apple,  see  Apple  blotch 
Calves,  Tests  to  determine  feeds 
responsible  for  unthriftiness 

of 165-67 

Carlinville  experiment  field,  crop 
yields  in  soil  experi- 
ments    409,410 

CARNATION  STEM  ROT  AND 

ITS  CONTROL 577-607 

Carnations 

Branch  rot    583 

Stem  rot 

Conditions  influencing  growth 
of  parasite  and  host.  .  .  .584—97 

Control  of 599-606 

Conclusions    and    recommen- 
dations   6'06-07 

Fungus 585-86 

Carthage    experiment   field,    Crop 

yields  in  soil  experiments. 411,  413 
Cattle,  Feeding  tests  for  forage 

poisoning  of 163-69 

See  also  Dairy  cows,  Steers 
Chicago,  Cost  of  milk  production 

for 344-64 

Clayton    experiment    field,    Crop 

yields  in  soil  experiments. 412,  413 
Cleistothecopsis  circinans  ....  507,  530 

CLIMATE  OF  ILLINOIS 1-125 

Clover,  Red,  germination  at  var- 
ious temperatures  25 

Colletotrichum  erumpens   ....  299-308 
Colletotrichum,  Falcate-spored 

forms  of   307-08 

Corn 

Days  required  for  germination 

at  various  temperatures 25 

Effect  of  rainfall  on  yield 28-30 

Temperature  for  growth 27 

Corn  silage,  see  Silage 

Corticium  vagum 579 

Cows,  see  Cattle,  Dairy  cows 
Cutler     experiment     field,     Crop 

yields  in  soil  experiments .  414—16 
Cyclones,   Weather    changes    pro- 
duced by 5,  9 

Cytosporas 

Bibliography 377-79 

on  Rosaceous  hosts 374-75 


INDEX 


611 


PAGE 

DA1HY  COWS,  A  STUDY  OF 
THE  RELATIVE  RELIA- 
BILITY OF  OFFICIAL 

TESTS  OF 321-39 

Dairy  cows 
Official   tests 

Comparison  of  seven-day  test 
and    seven-day    test    eight 
mouths  after  calving.  .  .334-36 
Comparison     of     seven-and 

thirty-day  tests    333-34 

Conclusions .'539 

Correlation  between  semioffi- 
cial and 337-38 

Explanation  of 323-24 

Plan  of  investigation 325 

Records 324-2.1 

Relation    of    fat    percentage 

to  test  period 327-28 

Variability  in  percentage  of 

fat 330-32 

Semiofficial  tests 

Accuracy 325-27 

Correlation     between     seven- 
day  and   337-38 

Explanation  of 324 

Relation    of    fat    percentage 

to  test  period 328-30 

Variability  in  percentage  of 

fat 332-33 

Used  in  tests 323 

Dairying,  see  Milk  production 
DeKalb    experiment    field,    Crop 

yields  in  soil  experiments.  .417-19 
Variety  tests  of  spring 

wheat 318,319 

Dixon     experiment     field,     Crop 

yields  in  soil  experiments .  420-22 
Drainage,    Effect    upon    loss    of 

limestone  from  soil.  .  .272-73,  293 
Dubois     experiment     field,     Crop 

yields  in  soil  experiments .  423-24 
Dusting  apple  trees  for  control  of 

apple  blotch   551,  552 

Compared    with    liquid    spray- 
ing   568,  569 

Edgewood  experiment  field,  Lime- 
stone on 267-68 

Enficld     experiment    field,     Crop 

yields  in  soil  experiments.425,  427 
Experiment  fields,  see  Soil  experi- 
ment fields,  names  of  particu- 
lar fields 
lowing     experiment     field,     Crop 

yields  in  soil  experiments .  426,  427 
Fairfield    experiment    field,    Crop 
yields  in  soil  experiments.  .  .428-30 

Fertilizers 402-03 

Commercial,    Influence   on   car- 
nation stem  rot  of 587-88 


PACK 

Manures,    Influence    on    carna- 
tion stem  rot  of 586-87 

Commercial  value  of.  .155—59,  354 

FERTILIZING     CONSTITU- 
ENTS    EXCRETED     BY 
TWO-YEAR-OLD 
STEERS 127-62 

Flax,      germination     at     various 

temperatures 25 

Flora,  111.,  Spraying  experi- 
ments   553-75 

FORAGE  POISONING  IN  CAT- 
TLE AND  HORSES,  FIELD 
INVESTIGATIONS  OF..  163-76 

Serum  developed   171 

Serum  treatment   ..171-72,174,175 

Friend  spray  gun 571 

Frost,  Time  of,  in  Illinois 46-47 

Fungicides,  Experiments  for  con- 
trol of  snapdragon   rust.. 541-44 
See  also  Sprays 

Galesburg  experiment  field,  Crop 

yields  in  soil  experiments. 43 1-34 

Grafting,  Influence  of  care  in. 252-53 

Grain  system  of  farming  on  ex- 
periment fields 401-02 

Harristown,     111.,     Feeding     test 

with  suspected  silage  at.  .  .168-69 

Hartsburg  experiment  field,  Crop 

yields  in  soil  experiments. 435-36 

Holstein-Friesian      dairy      cattle 

used  in  tests 323 

Horses,  Forage  poisoning  investi- 
gations   169-75 

Serum  treatment  .  .  .171-72,  174,  175 

Illinois,  Climate   1-125 

ILLINOIS  CROP  YIELDS 
FROM  SOIL  EXPERI- 
MENT FIELDS  397-503 

Joliet     experiment     field,     Crop 

yields  in  soil  experiments. 437-38 

Kewanee    experiment   field,    Crop 

yields  in  soil  experiments.  .  .  .439 

Lamoille    experiment    field,    Crop 

yields  in  soil  experiments. 440-41 

Lebanon    experiment    field,    Crop 

yields  in  soil  experiments .  442-44 

LIMESTONE     ACTION     ON 

ACID  SOILS 265-96 

Results  from  Newton  field .  .  268-85 
Results  from  Odin  field 286-95 

Limestone 

Comparative  effect  of  light  and 

heavy    applications.  . 286,  288,  291 
Comparative  value  of  high-cal- 
cium and  dolomitic 274-80 

Effect  of  degree  of  fineness.  .280-82 
Effect    of    drainage    upon    loss 
of 272,293 


612 


YOM'MK    1") 


PAGE 

Effect  on  surface  soil 270 

Influence    on    subsurface    and 

subsoil  .   ...273-74,282-85,291-93 
Live-stock  fanning  on  experiment 

fields 401 

McXabb    experiment    field,    Crop 

yield  in  soil  experiments. 445,  447 
Manure,  see  Fertilizers 
Motor iological  summary,  111.  Exp. 

Sta.   (1889-1916)   * 55-64 

MILK     PRODUCTION,     COST 

OF 341-64 

Bases  of  calculation 344-45 

Conclusions 364 

Cow  as  unit  in  determining. 357-64 

Expenses 360-64 

Xet  cow  cost 362-64 

Returns   362-63 

Dairy  herd  as  unit  in  determin- 
ing   346-57 

Expenses 347-52 

Net  herd  cost 354-56 

Returns 353-54 

Farm  as  unit  in  determining. 345-46 

Source  of  data 345 

See  also  Dairy  cows 
Minonk    experiment    field,    Crop 

yields  in  soil  experiments .  446,  447 

Mold  on  onion  sets 507 

Morrow  plots 401 

Crop     yields     in     soil     experi- 
ments    486-87 

Mt.  Morris  experiment  field,  Crop 

yields  in  soil  experiments. 448-49 

Xeck  rot  of  onion  sets 507 

Xeoga,     111.,     Experiments     with 

winter-injured  peach  trees. 386-87 
Xewton    experiment    field,    Crop 

yields  in  soil  experiments.  .450-54 
Limestone  experiment  on ...  .268-85 
Xitrogen  excreted  by  steers.  .  .143-50 
Oats,  germination  at  various  tem- 
peratures        25 

Oblong     experiment     field,     Crop 

yields  in  soil  experiments .  .  .  455-56 
Odin  experiment  field,  Crop  yields 

in  soil  experiments 457-61 

Limestone  experiments  on ...  286-95 
Olney,  111.,  Experiment  with  win- 
ter-injured  peach  trees.  .  .387-93 
OXIOX    SETS,    BLACK    SPOT 

OF 505-32 

Bibliography 532 

Causal  fungus 509-11 

Control  of 531-32 

Morphology 529 

Perithecium 511-12 

Taxonomic  position  of  asciger- 

ous  stage 529-30 

Type  of  disease 508-09 


PAGE 
Oquawka   experiment   field,   Crop 

yields  in  soil  experiment.  .462-63 
Ottawa,  111.,  Forage  poisoning  in- 
vestigations at 169-76 

Pana  experiment  field,  Crop  yields 

in  soil  experiments 463-65 

PEACH  TREES,  THE  PRUN- 
ING OF  WINTER-IN- 
JURED   381-94 

Phosphorus  excreted  by  steers .  150-55 

Phyllosticta  straminella 308-312 

Poff  Orchard,  experiments  at.. 387-93 
Pumpkin     seed,     germination     at 

various  temperatures 25 

Rainfall  in  Illinois 

10-22,  55-64,  65-119 

Raleigh    experiment    field,    Crop 

yields  in  soil  experiments .  466-67 
Rhizoctonia,  Temperature  best  for 

growth  of  culture 593 

EhizoctontO'  Solani 579 

Rhubarb  Anthracnose 299-308 

Fungus 300-05 

RHUBARB     DISEASES,     TWO 

ILLINOIS 297-312 

Rhubarb  leaf  spot 308-12 

Fungus 310-12 

Rockford   experiment   field,   Crop 

yields  in  soil  experiments. 468-72 
Rosaceous  twigs,  Fungi  on.  .  .  .372-75 
Rye,  germination  at  various  tem- 
peratures        25 

Seedlings,  Experiments  with  ap- 
ple   254-64 

Sidell      experiment      field,     Crop 

yields  in  soil  experiments .  473-74 
Silage,    Feeding    tests   with    sus- 
pected   163-69 

Smudge  on  onion  sets 507 

SNAPDRAGON  RUST 533-48 

Control ,.  .541-47 

Fungus,  Description  of 538 

History  and  distribution.  . .  .535-36 
Host     relationship     and     resis- 
tance   538-41 

In  the  field 547 

Prevention  and  control 541-47 

Recommendations 548 

Seed  not  carriers  of 546-47 

Summary 548 

Symptoms 536-38 

Snowfall  in   Illinois 22-24 

Soil 

Disinfection  of 599-602 

Limestone  action  on  acid .  . .  265-96 
Moisture     affecting     carnation 

stem  rot 595-97 

Steam  sterilization    602-06 

Temperature  of.  ...  42,  43,  44,  45,  46 


IXUEX 


613 


PAGE 

Soil  experiment  fields 

Illinois  crop  yields  from.  .  .397-503 

List  of 399,503 

Materials  for  soil  treatment  .402-0:? 

Rotations 401-02 

Systems  of  farming 401-02 

Sparta     experiment     field,     Crop 

yields  in  soil  experiments.  .475—76 
Spraying  experiments 

for  control  of  apple  blotch .  .  549-75 
Dusting  and  liquid  spraying 

compared 568,569 

Incidental  observations    .... 

561,570-71,573,575 

Objects 551,561 

Recommendations 575 

Summary  of  results,  1916.  .  .  .560 

1917 570 

1918 573 

for      control      of      snapdragon 

rust 541-44 

Sprays  for  apple  trees 

Arsenate  of  lead 551,  552 

with  lime  sulfur .568,  569 

Bordeaux 551 

Formula 552 

with  lime  sulfur,  see  Sprays 
for  apple  trees,  Lime  sulfur 
Copper  sulfate   .  .  .551,  552,  562,  563 

Lime  sulfur    551,552,562,563 

arsenate  of  lead 562,  563 

copper  sulfur  mixture.  .  .562,  563 
Lime  sulfur  and  Bordeaux 

Effect   of   interchanging.  .559-60 

Relative  values 

553-55,  563-65,  571-73 

Value    of    different    applica- 
tions  ..555-59,565-68,573,574 

Scalecide    551,  552,  562,  563 

Spring  Valley  experiment  field, 
Crop  yields  in  soil  experi- 
ments    477 

Steam  sterilization  for  control  of 

carnation  stem  rot 602-06 

Steers,  Experiments  to  determine 
fertilizing  constituents  ex- 
creted by  two-year-old ....  127-62 

Conclusions 161-62 

Equipment  and  methods  of  ex- 
periment      131 

Feces 

Amount 133-34 

Chemical  composition.  .  .  .  135,  136 
Feeds 

Amount 132-33 

Composition 133 

Cost 157 

Rations 129-31 

Financial  statement 155-59 

Nitrogen  excreted    143-50 


PAGE 

Organic  matter 

consumed 141,  143 

excreted 138-40,  141, 142 

Phosphorus  excreted 150-55 

Summary 159-61 

Urine 

Amounts 136-37 

Collection  and  sampling....    131 

Composition 136,  137-38 

'Stem  rot,  Carnation,  sec  Carnations 
Sunshine,  average  amount  for  Illi- 
nois        51 

Syringing,  Effect   on  snapdragon 

rust  of 545-46 

Temperature  of  Illinois 25-46 

Meteorological  summary  (1889- 

1916) 55-64 

Records 121-25 

Timothy,   germination  at  various 

temperatures 25 

Toledo     experiment     field,     Crop 

yields  in  soil  experiments. 478-79 
Union     Grove     experiment     field, 
Crop    yields    in    soil    experi- 
ments    480-82 

Unionville  experiment  field,  Crop 

yields  in  soil  experiments. 483-85 
Urbana,   Variety  tests   of  spring 

wheat 317,319 

Urbana    experiment    field,    Crop 

yields  in  soil  experiments. 486-97 

Valsas  on  fruits 376 

on  Rosaceous  hosts 372-73 

Vermicularia  cirdnans. .  .507,  529,  530 

V ermiculariose  on  onion  sets 507 

Virginia    experiment    field,    Crop  . 
yields  in  soil  experiments.498-500 

Volutella  circinans .507-32 

Volutella,    Falcate-spored    forms 

of 307 

Voris  Orchard,  experiments  at. 386-87 
Weather 

affecting  apple  blotch 553 

maps  .    . 6,  7 

See  also  Climate 
West  Salem  experiment  field,  Crop 

yields  in  soil  experiments.  .  .501-02 
Wheat,    germination    at    various 

temperatures 25 

WHEAT,   SPRING,   FOR   ILLI- 
NOIS   313-20 

Culture 315 

Drills 316-17 

Time  to  sow 315-16 

Variety  tests 317-18 

Yields  and  value 318-20 

Wind   in   Illinois 48-50,55-64 

Winter  injury  to  peach  trees.  .383-94 


UNIVERSITY  OF  ILLINOIS-URBANA 


